Josephus’ Circle
September 13th, 2009
I saw this interesting problem on The Daily WTF the other day:
Josephus and forty of his fellow soldiers retreated from the siege of Yodfat to a small cave in the hills. Surrounded by the Roman legion with no chance of escape, the soldiers saw no other choice but to commit suicide. Like the people of [...]
The Limit of (1+1/n)^n
May 20th, 2009
I heard our professor Dales say a cool thing in one of the lectures a few months back, and I only got around to writing it down now.
The question is simple: What does…
… tend to as n tends to infinity?
Here are two arguments:
1. The inside of the bracket goes to 1 as n goes to [...]
How to Find a Mathematician’s Hat Colour
May 6th, 2009
I recently came across this really interesting puzzle:
Three players enter a room and a red or blue hat is placed on each person’s head. The color of each hat is determined by a coin toss, with the outcome of one coin toss having no effect on the others. Each person can see the other players’ [...]
Buffon’s needle problem
April 8th, 2009
Ok, this is an eighteenth century problem first proposed by Georges-Louis Leclerc, Comte de Buffon (Yes that is only one name!). SupposeĀ a 2 inch needle is randomly thrown or dropped onto a floor made up of wooden boards which are also 2 inches wide and are placed side by side. Now the question is what [...]
Why is 0.99999… = 1?
March 17th, 2009
A cool thing I learned a long time ago is that 0.99999… = 1. And I mean exactly equal. Not just “very close to”. EXACTLY equal.
Behold the proof!
Let a = 0.111111…
Then 10a = 1.11111…
10a - a = 1.11111… - 0.11111…
9a = 1.
But 9 times 0.11111… is 0.99999….
So 0.999999…. is exactly equal to 1!
This has some [...]
Finding The Square Root of i
March 11th, 2009
Some years ago, when I first learned about imaginary numbers, I asked myself the inevitable question - “What’s the square root of i?”
Okay, so i is the square root of -1. I had come to grips with that concept. But after that, when you start thinking about it… surely the square root of i must [...]
Review: The Mathematics of Oz by Clifford A. Pickover
February 28th, 2009
The Mathematics of Oz: Mental Gymnastics form Beyond the Edge
This is a math puzzle book, and quite a nice short sci-fi story as well. It follows good ol’ Dorothy , as an alien (Oz) captures her, her faithful companion Toto and the entirety of Kansas to perform odd experiments. Particularly mathematical experiments on Dorothy who [...]
Nontransitive Dice
February 26th, 2009
Hey, let’s play a game!
I’ve got 4 dice here. We both pick a die, and then roll to see who gets the higher number. And since you’re my guest, I’ll let you pick your die first, and then I’ll pick mine. Sounds good?
Oh, I almost forgot to mention. My dice are numbered a bit strangely…
If [...]
Why Convergence Matters
February 23rd, 2009
We math geeks like to play. And one thing we like to play with a lot are series. A series is an infinite row of numbers following a certain rule, all added up. Let me show you two examples:
S1 = 1 + 1 + 1 + 1 + 1 + 1 + 1 + …
S2 [...]
Why are The Buses Fullest in The City Centre?
February 15th, 2009
I’ve been taking buses for a long time. One thing I noticed is that the buses are fullest in the city centre.
Now that’s kind of obvious. After all, most people who take the bus are going either to or from the city centre. It makes sense the buses are packed full of people there.
But that’s [...]
